1. Field of the Invention
The present invention relates to turbines. More particularly, the present invention relates to steam turbines, gas turbines, process turbines and gas compressors. More particularly, the present invention relates to such turbines where adjacent sets of blades are counter-rotatable with respect to each other.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
A steam turbine is a device that extracts thermal energy from pressurized steam and uses it to do mechanical work on a rotating output shaft. Because the turbine generates rotary motion, it is particularly suited to be used to drive an electrical generator. Approximately 90% of all electrical generation in the United States is by the use of steam turbines. The steam turbine is a form of heat engine that derives much of its improvement in thermodynamic efficiency from the use of multiple stages in the expansion of the steam. Steam turbines are made in a variety of sizes ranging from small (i.e. less than 0.75 kW) to approximately 1,500,000 kW. The small units are used as mechanical drives for pumps, compressors and other shaft-driven equipment. Large turbines are used to generate electricity.
Turbine blades are of two basic types, blades and nozzles. Blades move entirely due to the impact of steam on them. Their profiles do not converge. This results in a steam velocity drop and essentially no pressure drop as steam moves through the blades. A turbine composed of blades alternating with fixed nozzles is called an impulse turbine, a Curtis turbine, a Rateau turbine, or a Brown-Curtis turbine. Nozzles appear similar to blades, but their profiles converge near the exit. This results in a steam pressure drop and velocity increase as steam moves through the nozzles. Nozzles move due to both the impact of steam on them and the reaction due to the high-velocity steam at the exit. A turbine composed of moving nozzles alternating with fixed nozzles is called a reaction turbine or a Parsons turbine.
Except for low-power applications, turbine blades are arranged in multiple stages in series, called compounding, which greatly improves efficiency at low speeds. A reaction stage is a row of fixed nozzles followed by a row of moving nozzles. Multiple reaction stages divide the pressure drop between the steam inlet and exhaust. Numerous small drops result in a pressure-compounded turbine. Impulse stages may be either pressure-compounded, velocity-compounded, or pressure-velocity compounded. A pressure-compounded impulse stage is a row of fixed nozzles followed by row of moving blades, with multiple stages for compounding. A velocity-compounded impulse stage is a row of fixed nozzles followed by two or more rows of moving blades alternating with rows of fixed blades. This divides the velocity drop across the stage into several smaller drops.
Condensing turbines are most commonly found in electrical power plants. These turbines exhaust steam from a boiler in a partially condensed state at a pressure well below atmospheric to a condenser. Non-condensing or back pressure turbines were most widely used for process steam applications. The exhaust pressure is controlled by a regulating valve to suit the needs of the process steam pressure. These are commonly found at refineries, district heating units, pulp and paper plants, and desalination facilities where large amounts of low-pressure process steam are needed. Reheat turbines are also almost used exclusively in electrical power plants. In a reheat turbine, steam flow exits from a high-pressure section of the turbine and is returned to the boiler where additional superheat is added. The steam goes back into an intermediate pressure section of the turbine and continues its expansion. Using reheat in a cycle increases the work output from the turbine and also the expansion reaches conclusion before the steam condenses. As such, this minimizes the erosion of the blades in the last rows. Extracting-type turbines are common in various applications. In an extracting-type turbine, steam is released from the various stages of the turbine and used for industrial process needs or sent to boiler feedwater heaters to improve overall cycle effect efficiency. Induction turbines introduce low-pressure steam at an intermediate stage to produce additional power.
A gas compressor is a mechanical device that increases the pressure of the gas by reducing its volume. Compressors are similar to pumps. Both increase the pressure on a fluid and both can transport the fluid through a pipe. Since gases are compressible, the compressor also reduces the volume of the gas. Axial-flow compressors are dynamic rotating compressors that use arrays of fan-like airfoils to progressively compress the working fluid. The arrays of airfoils are set in rows, usually as pairs, one rotating and one stationary. The rotating airfoils, also known as blades or rotors, accelerate the fluid. The stationary airfoils, also known as stators or vanes, decelerate and redirect the flow direction of the fluid preparing it for the rotor blades at the next stage. Axial compressors are almost always multi-stage, but the cross-sectional area of the gas passage diminishes along the compressor to maintain an optimal axial Mach number.
In such turbines, a fluid stream, under pressure, impinges on a set of blades (or buckets) connected to a central shaft to produce work. This results in changes in the angular velocity of the fluid stream. These changes in an angular velocity serve to strike the next set of blades connected to the shaft in the most efficient manner. There is an intermediate set of blades which are set at a different angle to realign the flow so as to impinge upon the next set of working blades at the most efficient angle. The set of intermediate blades in most equipment is currently fixed to the stationary element. This process uses approximately 40% of the working fluid energy without producing any work.
In the past, various patents and patent publications have issued relating to such turbines. For example, U.S. Pat. No. 4,648,788, issued on Mar. 10, 1987 to P. Jochum, describes a device and a fluid pressure generator that includes an annular casing which is peripherally mounted and driven in a through-flow channel. The interface of the annular casing forms part of the wall of the through-flow channel. The annular casing is provided with a number of propeller blades which extend radially inwardly into the through-flow channel and which are rotationally mounted on their individual pin shafts by means of which the magnitude of the thrust may be altered in a continuous manner and the direction of the operation of the thrust can be reset.
U.S. Pat. No. 4,969,325, issued on Nov. 13, 1992 Adamson et al., shows a turbofan engine having a counter-rotating partially-geared fan drive turbine. This turbofan engine has a fan section, a booster compressor disposed aft of the fan section relative to the flow of combustion gases through the engine, and a core section disposed aft the booster compressor. A low-pressure counterrotating turbine, disposed aft the core section, is used for driving the fans section and the booster compressor. The counterrotating turbine includes at least one set of rotating turbine blades and at least one set of oppositely rotating counterrotating turbine blades. A twin spool shaft is provided for coupling the turbine blades to the booster compressor and for coupling the counterrotating turbine blades to the fans section.
U.S. Pat. No. 6,278,197, issued on Aug. 21, 2001 the K. Appa, discloses a contra-rotating wind turbine system. A hub assembly is provided having inner and outer coaxial shafts telescopically related but radially spaced to permit independent rotation about a generally horizontal axis. A first set of rotor blades is mounted on the inner shaft at a plurality of circumferentially-spaced locations. The rotor blades extend radially away from the axis of rotation and positioned on the inner shaft for rotating the inner shaft in a first direction about the axis of rotation when subjected to wind-induced airflow. A second set of rotor blades is similarly mounted on the outer shaft axially spaced from the first set of rotor blades for rotating the outer shaft about the axis of rotation in an opposite direction.
U.S. Pat. No. 7,195,446, issued a Mar. 27, 2007 to Seda et al., provides a counter-rotating turbine engine that provides a low-pressure turbine inner rotor configured to rotate in a first direction and a low-pressure turbine outer rotor configured to rotate in a second direction that is opposite to the first rotational direction. At least one foil bearing is coupled to at least one of the inner and outer rotors so as to improve clearance control between a first rotating component and at least one of a second rotating component and a non-rotating component.
U.S. Pat. No. 7,290,386, issued on Nov. 6, 2007 to Orlando et al., teaches a counter-rotating gas turbine engine. A low-pressure turbine inner rotor includes a first plurality of turbine blade rows configured to rotate in a first direction and a low-pressure turbine outer rotor rotatably coupled to the inner rotor. The outer rotor includes a second plurality of turbine blade rows that are configured to rotate in a second direction that is opposite the first rotational direction of the inner rotor such that at least one of the second plurality of turbine blade rows is coupled axially forward of the first plurality of turbine blade rows.
U.S. Pat. No. 7,451,592, issued on Nov. 18, 2008 to Taylor et al., teaches a counter-rotating turbine engine which includes a gearbox. The turbine engine arrangement is provided with contra-rotating shafts and a gearbox which is also coupled to a shaft. The relative rotational speed ratio between the shafts can be determined with a first low-pressure turbine secured to the first shaft arranged to rotate at a lower speed but provide high work whilst a second low-pressure turbine secured to the second shaft rotates at a higher speed governed by the gearbox.
U.S. Pat. No. 8,393,853, issued on Mar. 12, 2013 to Sauer et al., provides a high-efficiency turbine and method of generating power. The turbine includes a plurality of blades that rotate in a single direction when exposed to a fluid flow. The plurality of blades are joined to the central shaft by a plurality of radial spokes disposed substantially perpendicular to the central shaft such that the rotating plurality of blades causes the shaft to rotate.
U.S. Patent Publication No. 2012/0049523, published on Mar. 1, 2012 to S. A. Bersiek, describes a wind jet turbine with fan blades located on an inner and outer surface of the cylinder so as to allow wind or liquid to pass through the inner and outer blades. The wind jet turbine has a first set of fan blades, a plurality of magnets that each has a magnetic field, a cylinder having an inside and outside surface that supports the first set of fan blades on the inside surface and coupled to the plurality of magnets, and at least one cable winding located apart from the magnets. The rotation of the cylinder results in the movement of the magnetic field across at least one cable winding.
U.S. Patent Publication No. 2013/0219859, published in Aug. 29, 2013 to Suciu et al., provides a counter-rotating low-pressure compressor and turbine. The compressor section includes a counter-rotating low-pressure compressor that includes outer and inner compressor blades interspersed with one another and configured to rotate in opposite directions to one another about an axis of rotation. A transmission couples at least one of the outer and inner compressor blades to a shaft. The turbine section includes a counter-rotating low-pressure turbine having an outer rotor that includes an outer set of turbine blades. An inner rotor has an inner set of turbine blades interspersed with the outer set of turbine blades. The outer rotor is configured to rotate in an opposite direction about the axis of rotation from the inner rotor. A gear system couples at least one of the outer and inner rotors to the shaft.
U.S. Patent Publication No. 2013/0230380, published on Sep. 5, 2013 to Allouche et al., discloses a rotating housing turbine. The housing has a side wall. The turbine blades are attached to the side wall. The turbine is completely open in the center so as to allow a space for solids and debris to be directed out of the turbine without jamming the spinning blades/side wall.
It is an object of the present invention to provide a turbine apparatus that uses a greater percentage of the energy of the working fluid.
It is another object of the present invention to provide a turbine apparatus that can be used so as to power components are directed back to primary driven equipment.
It is another object of the present invention to provide a steam turbine that is suitable for powering boiler feed pumps, auxiliary pumps, hydraulics, and electrical generators.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.